Atomic force microscopy (AFM) probes are often used to evaluate and measure features on a semiconductor product as the semiconductor product is being developed or fabricated into an integrated circuit device, for example. Conventional AFM probes typically include a silicon cantilever beam with a silicon tip (“AFM tip”) extending perpendicular to or at a slight angle (e.g., 10 degrees) relative to the cantilever beam. The AFM tip is often formed into a long and thin rod. The AFM tip is often etched to form a sharp apex small enough to fit into a deep feature. There are several high aspect ratio tips on the market made for imaging and measuring deep narrow features. Some high aspect ratio tips are made using a focused ion beam to machine the silicon tip into a long thin rod with an aspect ratio between about 7:1 and 10:1. Hence, an AFM tip with a 10:1 aspect ratio (i.e., length:diameter) may be able to reach 1000 nm into a 100 nm diameter trench. Other high aspect ratio tips may be formed using electron beam deposition (e.g., EBD tips) or may be carbon nanotubes with a diameter between about 10 nm and 80 nm, for example.
As technology progresses, the features of integrated circuits typically become smaller, and in some cases, deeper. Thus, the demands on the size and precision of movement of AFM probe tips tends to increase as well. The depth that an AFM tip can reach into a deep feature depends on the angle or orientation of the tip relative to the deep feature sidewalls. If the center line of the AFM tip is perpendicular to the wafer surface or parallel to the deep feature sidewalls, then the AFM tip can reach deepest a center region of the deep region. If a left side or left face of the AFM tip is parallel with or inverted relative to a left sidewall of the deep feature, then the AFM tip can reach deepest at a left side of the deep feature along its left sidewall. Such scan may be desirable to obtain an AFM image of the left sidewall or to measure the depth of the deep feature at the bottom left corner. However, without knowing the actual AFM tip orientation and without being able to control the actual tip orientation, the AFM image results may be misleading. Due to the size of the deep features being measured for semiconductor devices relative to the size of the AFM tip, the actual AFM tip orientation must be known and controlled to obtain accurate AFM images of the deep features. Hence, there is a need for a way to measure, adjust, and control the actual AFM tip orientation for a given scanner head and AFM tip setup.